DNAI2 mutations cause primary ciliary dyskinesia with defects in the outer dynein arm.
Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder characterized by chronic destructive airway disease and randomization of left/right body asymmetry. Males often have reduced fertility due to impaired sperm tail function. The complex PCD phenotype results from dysfunction of cilia of the airways and the embryonic node and the structurally related motile sperm flagella. This is associated with underlying ultrastructural defects that frequently involve the outer dynein arm (ODA) complexes that generate cilia and flagella movement. Applying a positional and functional candidate-gene approach, we identified homozygous loss-of-function DNAI2 mutations (IVS11+1G > A) in four individuals from a family with PCD and ODA defects. Further mutational screening of 105 unrelated PCD families detected two distinct homozygous mutations, including a nonsense (c.787C > T) and a splicing mutation (IVS3-3T > G) resulting in out-of-frame transcripts. Analysis of protein expression of the ODA intermediate chain DNAI2 showed sublocalization throughout respiratory cilia. Electron microscopy showed that mutant respiratory cells from these patients lacked DNAI2 protein expression and exhibited ODA defects. High-resolution immunofluorescence imaging demonstrated absence of the ODA heavy chains DNAH5 and DNAH9 from all DNAI2 mutant ciliary axonemes. In addition, we demonstrated complete or distal absence of DNAI2 from ciliary axonemes in respiratory cells of patients with mutations in genes encoding the ODA chains DNAH5 and DNAI1, respectively. Thus, DNAI2 and DNAH5 mutations affect assembly of proximal and distal ODA complexes, whereas DNAI1 mutations mainly disrupt assembly of proximal ODA complexes.
Loges
Niki Tomas
NT
Department of Pediatrics and Adolescent Medicine, University Hospital Freiburg, Freiburg, Germany.
Olbrich
Heike
H
Fenske
Lale
L
Mussaffi
Huda
H
Horvath
Judit
J
Fliegauf
Manfred
M
Kuhl
Heiner
H
Baktai
Gyorgy
G
Peterffy
Erzsebet
E
Chodhari
Rahul
R
Chung
Eddie M K
EM
Rutman
Andrew
A
O'Callaghan
Christopher
C
Blau
Hannah
H
Tiszlavicz
Laszlo
L
Voelkel
Katarzyna
K
Witt
Michal
M
Zietkiewicz
Ewa
E
Neesen
Juergen
J
Reinhardt
Richard
R
Mitchison
Hannah M
HM
Omran
Heymut
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D000483:Alleles; D002648:Child; D002675:Child, Preschool; D002923:Cilia / Q000235:genetics* / Q000648:ultrastructure; D003241:Consanguinity; D004252:DNA Mutational Analysis; D004398:Dyneins / Q000737:chemistry / Q000235:genetics* / Q000648:ultrastructure*; D005091:Exons; D005260:Female; D005407:Flagella / Q000235:genetics; D005787:Gene Frequency; D008040:Genetic Linkage; D006801:Humans; D007619:Kartagener Syndrome / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide; D012326:RNA Splicing; D017422:Sequence Analysis, DNA; D055815:Young Adult
D004398:Dyneins